Propulsion apparatus actuated by successive charges of detonating materials



July 18, 1950 R. H. GODDARD 2,515,543

PROPULSION APPARATUS ACTUATED BY SUCCESSIVE CHARGES OF DETONATING MATERIALS 5 Sheets-Sheet 1 Filed May 21, 1945 ATTY.

July 18, 1950 R. H. GODDARD 2,515,643

PROPULSION APPARATUS ACTUATED BY SUCCESSIVE CHARGES 0F DETONATING MATERIALS Filed May 21, 1945 5 Sheets-Sheet 2 INVENTOR.

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July 18, 1950 R. H. GODDARD 2,515,643

PROPULSION APPARATUS ACTUATED BY SUCCESSIVE v CHARGES 0F DETONATING MATERIALS Filed May 21, 1945 3 Sheets-Sheet 5 LIZ I N VEN TOR.

, Arrx Patented July 18, 1950 PROPULSION APPARATUS ACTUATED BY SUCCESSIVEv CHARGES F DETONATING.

Robert H. Goddard; Annapolis, Md.; Esther G. Goddard, executrix of said Robert H. Godda d, deceased, assignor: of one-haltto The Daniel and; Florence, Guggenheim Foundation, New York, N. Y., acorporation of New York Application May 21, 1945, SerialNo. 594,846.

Claims.

This invention relates to apparatus. in. which propulsion is obtained by free detonation. of suc cessive unconfined charges of explosive material Withina surrounding deflecting structure.

Free detonations are here defined as those occurring at a sufficient distance from relatively fixedsurfaces to produce no seriously disruptive efiects on said surfaces, as contrasted with confined detonations taking place in substantial- 1y enclosed containers. In a prior Patent, No. 2,396,566 issued March 12, 1946; I have disclosed apparatus in which explosive material in the form of a cylindrical rod or column isdetonated on the axis of a 90 cone, and from the inner surface of which cone the resulting gases are axially deflected. The gases pass radially outward from the rod or column in the form of a thin-walled expanding cylinder and are deflected without substantial interference.

For a thicker detonating column, however, or

one from which the gases pass outward in the form of a cylinder of considerable thickness, the gases deflected from near the vertex of the cone will pass through and interfere with the gases passing outward toward the wider parts of the cone. I Itis the generalobject of my present invention to avoid such interference and also to. attain maximum effectiveness. More specifically, it is my object to cause all the products of detonation to travel in substantially the same deflected direction, and to minimize the mechanical forces on the deflecting surfaces, while maintaining the momentum produced by said forces.

My invention further relates to. certain arrangements and combinations of parts which will be hereinafter described and more particularly pointed out in the appended claims.

Preferred forms of the invention are shown in the drawings in which Fig. 1 is a side elevation, partly in section, showing one form. of my propulsion apparatus;

Fig. 2 is a sectional bottom view, taken along the line 2--2 in Fi 1;.

Fig. 3 is a fragmentary enlarged perspective view of certain parts shown inFig, 1;. V

Fig. 3a: is a further enlarged detailsectional- View, taken substantially along, the line. 3a 3a in Fig. 3; a v Fig. 4 is an enlarged sectional, side-elevation of certain parts shown in Fig. .1; i

Fig. 4a is a detail. sectional plan. vi w. taken in. the. directionrof the arrow- Acin. 4;

Fig. lb is an enlarged fragmentary side eleva tion. of a spreading device, looking in the direction of the arrow 4b in Fig. 4;

Fig. 5 .is a sectional, side elevation of an. ignition device to be described;

Fig. 6 is a diagrarmnaticv view illustrating the operation of my propulsion apparatus;

Fig. 7 is a sectional side elevation of a. modified form of my invention;

Fig. 8 is a detail sectional. view of an ignition device taken along the line ;8-8, in Fig. 7.;

Fig.9 is a sectional side elevation of a further modification;

1 Fig. 10 is a partial sectional; side elevation of another form. of. my invention;

Figure 10a is an enlarged detail. sectional view of certain. parts-shown: in Fig. '10;

t Fig. 10b is asi-milar view of a modified:.struc ure;

Figs. 11 and 12 are sectional side elevations of additional forms of my invention;

Fig. 12a is a fragmentary view, looking in: the :direction of the arrow 12a in Fig. 12;

Fig. 13 is a plan view showing angularly ad justable: deflecting members Fig. 14 is a perspective view, partly insection, showing mechanism for angularly adjusting the deflectors;

Fig. 15 is a partial sectional side elevation of apparatus for opening a central passage through an air craft and Fig. 16- is a sectional plan-view taken along the line 16-46 in Fig. 15;

Referring to the construction shown in Figs. 1 to 6 inclusive, I have shown my invent-ion mounted in a rocket craft 20 having a stream-- lined and substantially conical front end portion 2!. The detonating material; consisting preferably of an intimate mixture of combustible and explosive liquids; is ejected under pressure from a discharge passage 22 within a mixing device 23.

The passage 22 opens rearward through an axial opening 24 in a forwardly arched partition 25,. As the charge 0 is ejected rearward (or down.- ward in Fig. 1) through the opening 24, it is expanded by a spreader 26, supported on spaced arms 2'! (Figs. 4' and 4a). As the column. of mixed liquid is discharged from the tube 22 and passes the spreader 26, it enters thedetonation chamber .311 in the form of a, hollow cone, as clearly shown in section in Fig. 1.

Any suitable mechanism may be provided for feeding the detonating material, from the tube 22 in the form of successive slugs or spaced charges. Such ejecting apparatus forms no part of my present invention but devices suitable for this purpose are shown in my prior Patent No. 2,465,525, issued March 29, 1949. The detonation chamber 38 is surrounded by a series of annular deflectors 32 supported on spaced arms or partitions 33 (Figs. 2 and 3), which arms are preferably hollow and relatively thin and are streamlined in cross-section.

The detonation charge C is ignited substantially in the position shown in Fig. 1, in which position it is spaced somewhat rearwardly from the partition 25 and spreader 26. The gases produced by the detonation pass radially outward between the annular deflectors 32, and are deflected rearward or downward in such manner that the different portions of gases do not cross and interfere with each other.

In order to produce a maximum propulsive effect, the gases are deflected as nearly rearward as possible. Accordingly, the rearmost deflectors are relatively short in section, while the foremost deflectors are relatively long and are substantially curved. The arms. 33 may be attached at their forward ends to the partition 25 or to any other convenient supporting structure.

I have shown improved means for igniting the charge C, which means comprises a small combustion chamber 46 (Fig. 5), mounted above the partition and supplied with suitable fuel and oxidizing materials through pipes 4|. These materials sustain a pilot light which is projected successively through a safety chamber 42 and a pilot opening 43. With this construction, the pilot flame will not be extinguished when the detonation takes place.

Co-operating with this pilot light I provide a groove or depression 45 (Fig. 4b) in the directing surface of the spreader 26. This groove is so formed and positioned that it directs a small streamer of the detonating mixture outward and directly toward the pilot opening 43, where it is ignited by the pilot flame. Upon ignition of this streamer of detonating material, the main column C is immediately ignited and detonated. The ignition device, as shown in Fig. 5, is preferably provided with a refractory and heat-resisting lining.

As the detonations take place in very rapid succession there is little chance for the deflectors to be cooled, either by outward radiation or by air flow across the deflecting surfaces. Therefore I find it desirable to form the deflecting blades of hollow construction, as shown in Figs.

3 and 3a. The liquid or gaseous coolant is supplied through the arms or partitions 33, which are also of hollow construction.

The coolant passes through openings 55 (Fig. 3) from the hollow arms 33 to a passage 56 extending along the bottom edge of each deflector 32. The coolant then flows upward through a perforated partition 51 into the spaces between stiffening partitions 58 and escapes through perforations 59 (Fi 3c) at the top edge of the deflector. The perforations 59 are protected from back pressure by a lip or shield 66. In this manner the deflectors 32 are effectively cooled. If the detonations follow each other in very rapid succession, air will be retarded from flowing back into the space between the deflectors and the detonation column to an extent which will prevent normal atmospheric density from being restored before the next detonation takes place. This lack of normal density will, however, be an advantage as it serves to increase the speed of the rearwardly-directed gases by reducing air interference.

The basic principle of my method of propulsion is shown in Fig. 6. A layer of detonating material is located at an average distance 46 from a surface 48 which makes an angle 49 with the detonating layer. This surface 48 may be metal or may consist of additional detonating material. At an average distance 50 from the layer 45 there is a deflecting surface 5|, placed at an angle 52 with respect to the layer 45. The gases from 45 are deflected by this surface 5| as indicated by the arrow at and opposite to the desired direction of propulsion.

If the deflecting surface 5| is close to or in contact with the detonating layer 45, the deflecting surface will be thrown off with great violence, owing to the intense pressure close to the material 45. At a short distance away from the material 45, both the high temperature and the high pressure of the gases will have been reduced, and the energy will have been largely converted to kinetic energy or mechanical motion. This transformation from temperature and pressure to kinetic energy is very efficient, as it takes place in too short a time for ionization equilibrium to have become established. The rapidity of the change accounts for the tremendously disruptive effects that are produced by detonation, as compared with the heating effects observed when substances of equivalent energy unite to produce a steady flame. Once the energy has been changed to kinetic energy, it remains in this form except as'decreased by impact against the air. Because of the low density of atmospheric air, the high velocity persists for a considerable distance.

The distance 46 from the layer 45 to the surface 48 is of importance. If 45 is in contact with 48, gases at the outer or free surface of 45 will move outward with great velocity, whereas gases from the part near 48 will move comparatively slowly. The result is that the first layers of gas which leave 45 will carry a large proportion of the whole energy of the detonating substance, since the energy depends on the square of the speed. Inasmuch as there is only a certain amount of energy available in the substance, the average velocity, which determines the propulsive effect, is in this case much less than the maximum.

The impulse or reaction will obviously be greatest if the average and maximum speeds are for practical purposes equal, or in other words if all parts of the substance 45 move eventually with the same velocity. The maximum velocity can be reduced and the average velocity increased by providing a substantial distance 46. The gases then begin to move away from each side 50 of the layer 45. The gas velocity from the part nearer the reflector 5| is thus reduced and the velocity from the part nearer 48 is increased, since the latter part leaves the vicinity of 48 after the former part has left 5| and no longer compresses said former part.

The advantage of the type of propulsion device shown in Fig. 1 will now be evident. The gases from the inner part of the cone move inward, thus relieving the pressure on the outer part and at the same time being directed axially rearward. Gases from the outer part of the cone diverge or spread out, and the'force on the deflectors is thereby reduced to a safe value, even at a short distance from the cone. 7

Modifications may be made, notably with -rergard-to the angle between the layer 4'5: and: the

surface, which is preferably another detonat- -ingbody. Also the size of the angle '52 and the shape of the deflector surface? 51 may be varied. The distance 50 between the surface 51 and the layer 45 may be increased considerably be yond the shortest practicable distance 50:, but should not be increased-to such an extent as to cause the gas speed to be reduced appreciably by the intervening air.

In the form shown in Fig. '7, the angle of the hollow cone (3' is reduced until the detonating material is very nearly in the form of a hollow cylinder. The chief advantage is the low loss by evaporation, if a cold oxidizing liquid such as liquid oxygen is used in the detonating mixture.

The deflectors 62 are shown as all. being located at a relatively short distance from the charge.

Strictly axial deflection can be secured only by having the deflectors progressively wider forwardly, so that the gases can leave axially. Since the distance to the deflectors in Fig. l is-substantially thesame for all, the forward deflectors are progressively wider, and hence have increased skin friction. This is avoided with vanes of constant width, as in Fig. 7, although the outward component-of velocity reduces somewhat the reactive effect.

The form shown in Fig. '7, in which flow takes place along the vane surface, is best adapted for moderate detonating gas speed. Inasmuch as the" vanes canbe fairly long without introducing too great resistance, each gas layer strikes only the part of the deflector which makes a considerable angle with the direction of the gases, thus that the ignition method shown in Fig. 1 is not applicable. Instead, the ignition device 63 (Fig. 8) is mounted inside one of the deflector support arms 64 and each charge is detonated as soon as its rearmost end reaches the pilot flame. The charge is substantially separated from the partition 65 and spreader 66 when the detonation takes place.

For gases with very high velocity, deflectors with straight sections as shown in Fig. 9 are preferably used in order to avoid the loss of speed produced when very high velocity gases slide over curved surfaces. The annular conical deflectors 10 are progressively of greater diameter forwardly, but not to such an extent as to cause the gas velocity to be much reduced by the air. With this offset or echelon arrangement, all of the gases may be deflected strictly rearward or axially, and without interference between the layers of gas striking the various deflectors. The igniter may consist of the pilot flame equipment already shown in Fig. l. The air resistance of the widest or forward deflector is reduced by an annular streamlined cap H.

A construction involving a wide rather than a narrow angle 49 (Fig. 6) is shown in Fig. 10. In this case, the angle 49 is 180, and the angle 50 is zero. The spreader here produces a flat sheet of detonating material C spaced from the flat deflector 16. This form is of advantage when a large extent of surface is to be pushed by means of directeddetonations, as several: fiat-chargeproducin'g devices 11 covering the entire surface may be used to produce such charges simultaneously, each being provided with a suitable spreader. The pilot flame is produced by an igniting equipment 19 similarto that shown in Figs. 5 and 8 but with the pilot hole flush with the surface of the deflector. A narrow guard or flange l8 is' usedaround the deflector, in order to direct the gases at the edge portion rearwardly. The spreader is shown enlarged in Fig. l-Oa. Each chargeC is open at its center and is spaced from the spreader to prevent injury. A sectional spreader 18 is shown in Fig. 1% for producing multiple layer detonating charges, reducing still further the maximum gas velocity. r

In Fig. 11 I have shown a system of deflectors from which the blast as a whole diverges widely instead of being deflected axially or rearwardly. The charge-C is cylindrical and ignition takes place b means of a pilot flame, as in Fig. l.- Arms 8| support the deflectors.

Although effective propulsion requires that the propelling jet be as nearly unidirectional as possible, the divergent blasts of Fig. 11 nevertheless are desirable for propulsion in air of appreciable density. In such. case, as much air as possible should be entrained by the detonating device and should be given a high rearward velocity. The gases ejected from the deflectors should mix rapidly and completely with the entrained air, and should rapidly impart to this air'any heat remaining in the gases.

In the construction shown in Fig. 12, many diverging blasts of gas from the deflectors 9t act uniformly on the entire mass of air in the expanding space between the air deflectors $2 and the cap or nose-piece 93 of. the air craft 9% that is being propelled. The air deflectors Q2, together with thedetonating charge ejector 9a .to which the deflectors are attached, are supported by arms 9t as shown in Fig. 12a. The forward ends of the ejector and the foremost deflector 9d are provided with streamlined caps.

Sufficient air cannot be admitted through the relatively narrow opening in the immediate vicinity of the blast deflectors 90, and hence annular passages between the air deflectors 92 are required. All the inner faces of the air deflectors are at the same angle with the craft axis, and the air deflectors are spaced axially so that the outwardly expanding gases encounter only such surfaces as are at this angle with the axis.

One advantage of locating the propelling systern forward of the craft is that said system may have at least the width of the craft. Hence, the resistance due to air compression at the forward end of the craft is, to a large extent, done away with, as air is drawn in by suction after each detonation.

My improved propulsion apparatus is applicable to propulsion through the air and also to propulsion in very low pressure regions at high altitudes. The blasts from the deflectors should be deflected outwardly for low altitudes and strictly rearwardly for high altitudes. This directive control may be obtained by using deflectors I 00 (Fig. 13) which are turnable about bearings in arms fill. The turning may be accomplished by providing bevel gears I82 (Fig. 14) between the deflectors I60, and rotating said gears by a rack bar H33 slidable in one of the arms IDI. The rack bar H13 may be guided by a roller I06 (Fig. 14). 1

By thus varying the angles of the deflectors I 00,

the entrained air may be utilized for propulsion at low elevations, whereas at a relatively high altitude the deflectors may be turned so as to cause the gases from these deflectors to pass rearward axially,

When the deflector system is located on the axis of the air craft and at the forward end of the craft, propulsion by blast gases directed strictly rearward requires an exhaust passage or duct H (Fig. 15 through the middle of the craft I l I. This passage may be covered by conical segments [l2 similar to the scoops of an orangepeel dredging bucket during the period of air entrainment. They are preferably bevelled at their rear edges H5 to provide a smooth surface and are each moved outward and rearward when desired by a pinion gear H6 and rack bar Ill (Fig. 16). A roller H8 steadies the rack bar.

From the fore-going description of several forms of my invention, it will be evident that I have provided propulsion apparatus in which interference of different portions of the detonating gases is effectively avoided and in which the gases are so deflected as to produce maximum efficiency.

Having thus described my invention and the advantages thereof, I do not wish to be limited to the details herein disclosed, otherwise than as set forth in the claims, but what I claim is:

1. Propulsion apparatus comprising an axial series of annular deflectors enclosing a detonating chamber, and means to present and detonate an explosive charge within said chamber and substantially spaced from said deflectors, said deflectors being of progressively decreasing width rearwardly of said apparatus.

2. Propulsion apparatus comprising an axial series of annular deflectors enclosing a detonating chamber, and means to present and detonate an explosive charge within said chamber and substantially spaced from said deflectors, said deflectors being of progressively decreasing width and decreasingly concave surface curvature rear.- wardly of said apparatus.

3. Propulsion apparatus comprising an axial .series of annular deflectors enclosing a detonating chamber, and means to present and detonate an explosive charge within said chamber and substantially spaced from said deflectors, said deflectors being rearwardly decreasingly concave on their rear and gas-engaging faces.

4. Propulsion apparatus comprising an axial series of annular deflectors enclosing a detonating chamber, and flxed arms crossing and supporting said deflectors, said arms and deflectors being of hollow construction and having communicating openings through which a fluid coolant may flow from said arms to said deflectors.

5. Propulsion apparatus as set forth in claim 4 in which the hollow deflectors are provided with discharge openings at their forward edges, and in which a rearwardly projecting shield prevents back pressure on said discharge openings.

ROBERT H. GODDARD.

REFERENCES CITED Ihe following references are of record in the file of this patent:

UNITED STATES PATENTS 'Date 

